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A171807 Emirps (A006567) p such that R(prime(p)) is prime. 0
37, 71, 157, 167, 199, 907, 953, 971, 991, 1151, 1193, 1213, 1223, 1231, 1237, 1279, 1283, 1381, 1429, 1471, 1499, 1523, 1583, 1597, 1601, 1619, 1669, 1811, 1831, 1867, 3299, 3343, 3347, 3371, 3373, 3391, 3463, 3467, 3469, 3527, 3541, 3719, 3767, 3803 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..44.

FORMULA

{n such that n is in A000040 and A006567(n) is in A000040 and A000040(n) is in A000040 and A006567(A000040(n)) is in A000040}.

EXAMPLE

a(1) = 37 because 37 and R(37) = 73 are prime, as are prime(37) = 157 and R(prime(37)) = 751. a(2) = 71 because 71 and R(71) = 17 are prime, as are prime(71) = R(prime(71)) = 353 (which is not an emirp because the reversal is the same prime). a(3) = 157 because 157 and R(157) = 751 are prime, as are prime(157) = R(prime(157)) = 919 (which is not an emirp because the reversal is the same prime). a(4) = 167 because 167 and R(157) = 671 are prime, as are prime(167) = 991 and R(prime(167)) = 199. a(5) = 199 because 199 and (199) = 991 are prime, as are prime(199) = 1217 and R(1217)= prime(912) = 7121.

MATHEMATICA

emQ[n_]:=Module[{idn=IntegerDigits[n], revidn}, revidn=Reverse[idn]; idn!= revidn && PrimeQ[FromDigits[revidn]] && PrimeQ[FromDigits[ Reverse[ IntegerDigits[ Prime[n]]]]]]; Select[Prime[Range[600]], emQ] (* Harvey P. Dale, Mar 01 2012 *)

CROSSREFS

Cf. A000040, A004086, A006567.

Sequence in context: A138396 A335484 A155087 * A178399 A044103 A044484

Adjacent sequences:  A171804 A171805 A171806 * A171808 A171809 A171810

KEYWORD

easy,nonn,less,base

AUTHOR

Jonathan Vos Post, Dec 18 2009

EXTENSIONS

More terms from R. J. Mathar, Jan 25 2010

STATUS

approved

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Last modified July 5 17:04 EDT 2020. Contains 335473 sequences. (Running on oeis4.)